Electrical alarm system



sew 14,1948. 7 RT 2,449,168 Y suacmrcu. ALARM SYSTEM Filed Nov; 18, 1947Jtva J/iEerz,

Patented Sept. 14, 1948 ELECTRICAL ALARM SYSTEM James J. Kertz. Jamaica,N. Y., assignor to Maurice Coleman, Brooklyn, N. Y.

Application November 18, 1947, Serial No. 786,653 3 Claims. (01.177-314) The present invention relates to electrical burglar alarmsystems.

An object of this invention is to provide a novel and improved burglaralarm system employing a very simple circuit.

A further object hereof is to provide a novel and improved burglar alarmcircuit adaptable to most existing systems which include a closedprotective circuit, so as to render them free from 'false alarms due tosome manner of loose connection in said protective circuit.

Another object of the present invention is to provide a novel andimproved electrical burglar alarm system of the character describedwhich is efiicient in carrying out the purposes for which it isdesigned.

Other objects and advantages will become apparent as this disclosureproceeds.

In the accompanying drawing, Fig. 1 shows an electrical wiring diagramof my new system and sets forth means easily added to existing systemsto make them false alarm proof.

In the drawing, the numerals l5 and I6 indicate electrical switchdevices connected in series, which are automatically set in closedcondition upon the shutting of doors and windows protected, as is wellknown in the art. Connected in series with these switch devices are anelectrical energy source H, the coil I8 of a relay l9, and for practicalreasons, an ammeter 20. This comprises what is termed in the parlance ofthe art, the protective circuit. One of the terminals of the protectivecircuit is a fixed switch contact point 23 of a switch mean-s indicatedgenerally by the numeral 22, and the other terminal of said protectivecircuit is connected to both the fixed switch contact point 24 of theswitch means 22, and the fixed switch contact point 28, adapted to becontacted by the armature 29 of the relay l9, when the relay coil I8 isactuated to attract said armature against action of a sprin When saidarmature 23 is not attracted to the relay coil l8, it is in contact witha fixed switch contact point 3|, which latter and the fixed contactpoint 25 of switch means 22, are connected to a terminal of an electricbell or other alarm means 32; said bell being in series connection witha source of electrical energy 34, connected to the fixed switch con-tactpoint 26 of the switch means 22. The armature 29 is connected to a fixedswitch con-tact point 21 of said switch means 22. Said contact point 21is in constant contact with the moveable component indicated generallyas 33, of said switch means 22. This move.-

able component 33 is preferably the segment oi a metal ring, axiallyrotatably mounted and pro vided with a turn knob 35. This may betermedthe alarm circuit. 1

It is to be noted that the switch means, 22 really comprises twoseparate switches manipulated by turning the single knob 35. One ofthese switches consists of the moveable member 33 and the contact point23, whose function isonly to open the protective circuit when the systemis to be in fully inoperative condition. Theo'ther of said switchesmanipulated by turning the knob 35 consists of the moveable member 33,whose extending integral brush tab 33 makes contact successively withthe contact points24, 25 and 26, in the order mentioned when the systemis set into operative condition, and in reverse order Wh n t e a m ystemis to remain inactive while any of the switch devices l5. and I6 may ormay notbe in intended open condition. y

Disregarding for the moment the resistances 3-5 and 31, the operation ofthe system described is as follows: 1 i

With the'moveable component of the'switch means 22, in the position asshown in. Fig. 1, the system is in inoperative condition. Notethatarmature. 23 is in contact with point 3!. Win- (lows and doors may beopened to open any of the switch devices l5 and I6. i

To place the system into operative condition, all windows and doors areshut whereby all switch devices l5 and iii are set in closedcondition.1N ow by turning knob 35 clockwise, component 33 will make contact withpoint 23. Nothing isqaccomplished thereby until contact tab 33' contactspoint 24, whereupon the protective circuit is closed and current fromsource I! flows through the relay coil l8, which now attracts to itthearmature 29. Upon being so moved, the armature breaks itsc-onta-ctwith point 3| and makes contact with point 28. Now, so long ascomponent 33 remains in contact withpoin-t 23, regardless of position ofthe tab 33', and there is no break in the protective circuit, thearmature 29. will remain so attracted, for said protective circuitremains closed by virtue of contact between armature 29 and point 3|.The ammeter, of course, serves as visible means showing that theprotective circuit is closed. If with tab 33 on point 24, the ammeter isnot actuated, the operator knows that either all the switches l5 and I5are not in closed condition, or that battery I1 is dead or some othercause maintains the; protective circuit open. He will therefore remedythis situation, if it occurs, until there is an am meter reading ofpredetermined scope.

Tab 33 is now moved to point 25. Nothing is accomplished thereby untiltab is in contact with both points 25 and 28, whose distance apart shallpermit this, whereupon the bell 32 willring because the bell circuitwhich includes the connecting conductor 36, is closed until said contacttab 33' is wholly in contact with point 26. Such ringing of the bell, isa means to test operation thereof. Now, with tab 33' wholly on point 26,the system is in operative condition, meaning, that if a break shouldoccur in the protective circuit, as for instance upon the opening of anyof the switch devices I5 or Hi, the relay coil l8 will cease will show asmall reading if any of the switch devices l5 and I6 are open, but willindicate a comparatively large reading when all such switch devices areclosed. Such shunting resistances may be across each switch device l5and It individually, or preferably as shown, in parallel with a seriesof such devices, The resistances are of course such as to have thesystem function as mentioned.

This shunting resistance'means may of course :be applied to any alarmsystem having a normally to be energized, the armature 29 will be movedby the stressed spring 30, to come in contact with point 3|, whereuponthe alarm circuit which includes the connection conductor 31, will beclosed and bell 32 actuated, thereby sounding an alarm. Turning knob 35so that tab 33' goes off point 25, will open said alarm circuit.

In normal use, where no break occurs in the protective circuit, with thesystem in operative condition as described, that iswhen tab 33' iswholly on contact point 26, to set the system into inoperativecondition, knob 35 is turned in counter-clockwise direction. When tab 33in its travel, contacts both points 25 and 26, the bell circuit whichincludes the connecting conductor 36, willbe closed and the alarmsounded momentarily for knob 35 is kept moving. Such momentary soundingof the alarm is assurance that theb'ell 32 is in working order. Passageof tab 33' from off point 26, opens the alarm circuit. The protectivecircuit remains on for which ammeter 20 is a check-up, until theprotective circult is opened when component 33moves out of contact frompoint 23, to the condition shown in Fig, 1, whereupon the relay coil I8is deenergized and its armature will return to contact 3|.

In practice, false alarms are sounded because of breaks in theprotective circuit, of slight momentary duration, caused by defects inthe switch devices l5 and H5 or in loose connections thereto. Soalthoughwhen the system is set in operative condition, and apparently allappears in good order, mere drafts of wind, for instance may set looseparts in motion, to cause the momentary breaks in the protectivecircuit. I have provided means to avoid the giving of the alarm undersuch However, if the break persists l circumstances. for'more'than aslight instant, the relay l9 will operate to actuate the bell 32.

To accomplish this, only the switch devices l5 and 16 are shunted byhigh resistance means 36 and 31, which may be of the variable type. Thecharacter of these high resistance shunts, is that upon a momentarybreak as mentioned, occurring in any of said switch devices i5 and Hi,while the system is in operative condition, the feeble current affordedinv the protective circuit through these resistances, shall togetherwith the effect of the existing but dying residual magnetism in therelay core, be sufficient to hold the armature attracted an instantduring which the said break repairs itself. Of course, if such breakpersists more than a moment, as occasioned by the opening of a door orwindow protected by said switch devices l5 and It, the relay will becomedeenergized to an extent to release the armature 29, though such feeblecurrent be flowing through the relay coil l8; such feeble current beinginsufficientto actuate the relay l9, by its own action.

It-is to be noted that upon contact of moveable switch component 22,with point 23, at setting the system into operative condition, theammeter closed protective circuit including a relay for control of thealarm circuit.

This invention is capable of numerous forms and various applicationswithout departing from the essential features herein disclosed and maybeapplied and used for instance to fire alarm or other alarm system.

It is therefore intended and desired that the embodiment shown herein bedeemed illustrative and not restrictive and that the patent shallcoverall patentable novelty herein set forth; reference being had to thefollowing claims rather than to the specific description herein toindicate the scope of this invention.

I claim:

1'. In an electrical alarm system of the character described, a switchmechanism comprising a first, second, third and fourth fixed switchcontact points and a moveable electrically conductive component adaptedin one position to be out of contact with said contact points, whenmoved in one direction to be positioned successively in contact withsaid first, second and third contact points, when moved in the oppositedirection to be successively in contact with said third, second andfirst contact points, also adapted to contact the second and thirdcontact points simultaneously and while in contact with any of thefirst, second or third contact points or between any two of them to bein electrical contact with the fourth contact point, an alarm circuithaving the second and third contact points as its respective terminals,a protective circuit including a relay; the first and fourth contactpoints being the respective terminals of said protective circuit; therelay including an armature and a fifth and sixth fixed switch contactpoints; said armature being in contact with the fifth contact pointwhile the relay is inactive and in contact with the sixth contact pointwhen the relay is actuated to move said armature away from said fifthcontact point; said fifth contact point being in electrical connectionwith the second contact point; the sixth contact point being inelectrical connection with one of the terminals of the protectivecircuit and said armature being in electrical connection with themoveable component of the switch mechanism.

2. In'an electrical alarm system of the character described, aprotective circuit including protective switch means adapted to be inclosed condition when the system is set into operative condition, arelay and a source of electrical energy in series electrical connectionvwith said switch means in said protective circuit, an alarm circuitcontrolled by said relay and high electrical resistance means shuntingonly said switch mechanism; said resistance means being characterized inthat upon a momentary break occurring in the shunted portion of theprotective circuit after the system is set into operative condition,sufiicient current will flow in the protective circuit to augment theaction of the residual magnetism in the relay core to maintain thearmature of the relay in its attracted position during such momentarycontinuance of such break to avoid operation of the alarm circuit duringsuch momentary continuance of said break, and further characterized inthat while resistance means being characterized in that upon a momentarybreak occurring in the shunted portion of the protective circuit afterthe system is set into operative condition, sufficient current will flowin the protective circuit to augment the action of the residualmagnetism in the relay core to maintain the armature of the relay in itsattracted position during such momentary continuance of such break toavoid operation of the alarm circuit during such momentary continuanceof such break, and further characterized in that while said armature isin released position the current flowing in the protective circuit isinsufiicient to actuate the relay to attract the armature during anybreak in said switch means in the protective circuit.

JAMES J. KERTZ.

